Span-to-depth ratios for preliminary sizing of beams up to 10 m span Select the correct set of safe span/depth ratios for cantilever, simply supported, and continuous beams.

Introduction:
Span/depth ratios help in preliminary sizing to meet deflection control before detailed analysis. For spans up to about 10 m, common guideline values exist for different support conditions.

Given Data / Assumptions:

• Ordinary reinforced concrete beams.
• Typical service loads and normal exposure.
• Preliminary sizing stage (to be refined later).

Concept / Approach:

Cantilevers deflect more for the same depth, so they require smaller span/depth ratios. Continuous beams are stiffer than simply supported and can use a larger ratio.

Step-by-Step Solution:

Verification / Alternative check:

Final designs should include modification factors for tension reinforcement percentage, compression steel, and flanged sections.

Why Other Options Are Wrong:

Other sets either over- or under-estimate stiffness for the given support system.

Common Pitfalls:

Treating these ratios as code limits rather than starting points; ignoring long-term creep and shrinkage effects.

Final Answer:

Cantilever 7; Simply supported 20; Continuous 26